Fuel feed system

ABSTRACT

Disclosed herein is a carburetor comprising an air induction housing adapted to be connected to the crankcase of an engine and including a pair of air induction passages, a separate high speed fuel nozzle communicating with each of the induction passages and with at least one of the high speed nozzles communicating with a high speed fuel inlet port at the exterior surface of the air induction housing, a low speed fuel nozzle communicating with one of the induction passages and with a low speed fuel inlet port at the exterior surface of the air induction housing, and a fuel feed housing adapted to be mounted on the air induction housing in overlying relation to the high and low speed inlet ports and including a first diaphragm controlled, fuel flow regulating valve communicating with the high speed inlet port in the air induction housing and adapted to be connected to a source of fuel, and a second diaphragm controlled, fuel flow regulating valve communicating with the low speed port in the air induction housing and adapted to be connected to a source of fuel.

[ FUEL FEED SYSTEM [75] Inventors: Clarence E. Blanchard, Kenosha,

Wis.; Robert K. Turner, Waukegan; Chester DuBois, Zion, both of ill.

[73] Assignee: Outboard Marine Corporation,

' Waukegan, Ill.

[22] Filed: July 20, 1972 [21] App]. No.: 273,377

[52] US. 261/23 A, 26l/69 A, 26l/DIG. 68,

[451 Sept. 18, i973 Primary Examiner--Tim R. Miles Attorney-Robert E.Clemency et al.

[57] ABSTRACT Disclosed herein is a carburetor comprising an airinduction housing adapted to be connected to the crankcase of an engineand including a pair of air induction passages, a separate high speedfuel nozzle communicating with each of the induction passages and withat least one of the high speed nozzles communicating with a high speedfuel inlet port at the exterior surface of the air induction housing, alow speed fuel nozzle commu-' nicating with one of the inductionpassages and with a low speed fuel inlet port at the exterior surface ofthe air induction housing, and a fuel feed housing adapted to be mountedon the air induction housing in overlying relation to the high and lowspeed inlet ports and including a first diaphragm controlled, fuel flowregulating valve communicating with the high speed inlet port in the airinduction housing and adapted to be connected to a source of fuel, and asecond diaphragm controlled, fuel flow regulating valve communicatingwith the low speed port in the air induction housing and adapted to beconnected to a source of fuel.

12 Claims, 7 Drawing Figures [51] Int. Cl. F02m 9/06 [58] Field ofSearch 26l/DlG. 68, 69 A,

261/23 A, 41 D, 35, 67; 123/73 R, 59 B [56] References Cited UNITEDSTATES PATENTS 2,216,422 l0/l940 Schimanek 26l/DIG. 68 2,345,168 3/1944Wirth et a1 26l/DlG. 68

3,085,791 4/1963 Phillips 261/DIG. 68 3,269,374 8/1966 Conover 123/59 B3,272,485 9/1966 Newman 261/DIG. 68 3,377,024 4/1268 Nutten et al...,26l/DIG. 68 3,453,994 7/1969 Nutten et al 261/DIG. 68

t rust. Fess srsrIsM BACKGROUND OF THE INVENTION The invention relatesgenerally to arrangements for feeding fuel to internal combustionengines and particularly to carburetor arrangements for high speedracing engines.

In past carburetor arrangements, diaphragm controlled regulating valveshave been in common use. Typically, a single regulating valve controlledfuel flow to both high speed and low speed nozzles which, in turn,communicated with a single air induction passage. In addition, in priortypical carburetor constructions, the fuel flow regulating arrangementwas embodied in an integral portion of the carburetor body or housingand was not readily separable therefrom.

SUMMARY OF THE INVENTION The invention provides a carburetor arrangementcomprising separate fuel delivering systems respectively includingseparate diaphragm controlled, regu' lating valves for controlling fuelflow to each of a high speed nozzle and a low speed nozzle.

The invention also provides a carburetor arrangement including an airinduction housing which is adapted to be mounted to the crankcase of atwostroke engine and which includes a plurality of airinduction passageseach including a high speed nozzle. At least some of the air inductionpassages also include a low speed nozzle. Also included are high and lowspeed fuel inlet ports located on the outer surface of the air inductionhousing and respectively communicating with the high and low speednozzles.

Further in accordance with the invention, there is provided a separablefuel feed housing which is detachably mountable on the air inductionhousing and which includes separate high and low speed outlet portslocated so as to mate with the high and low speed inlet ports in the airinduction housing when the fuel feed housing is mounted on the airinduction housing.

Still further in accordance with the invention, the fuel feed housingincludes two separate high and low speed fuel delivering systems eachincluding a diaphragm controlled, fuel regulating valve of the demandtype, which valves communicate with a fuel source and which respectivelycommunicate with the high and low speed outlet ports in the fuel feedhousing. Each of the high and low speed fuel delivery systems alsoincludes a removable orifice element or other means for additionallyregulating fuelflow.

Still further in accordance with one aspect of the invention, theillustrated carburetor arrangement is adapted for use with afour-cylinder two-stroke engine including four separate crankcasechambers. The carburetor arrangement comprises an air induction housingincluding four nested carburetor units each communicating with aseparate one of the crankcase chamhers through a reed valve box and eachincluding two air induction passages which are preferably circular incross section. Each of the air induction passages in each carburetorunit includes a high speed nozzle and one of the barrels or airinduction passages in each carburetor unit includes a low speed nozzle.Preferably all eight barrels or air induction passages are approximatelyof the same construction and include commonly operated throttle valves.

Also in the preferred embodiment of the invention, each carburetor unithas associated therewith an individual fuel feed housing which isdetachably mounted on the air induction housing and which includesseparate high and low speed fuel delivery systems each including a fuelflow regulating valve and provision for selective insertion of orificeelements which can include orifices of various sizes so as to tailor thehigh and low speed fuel delivery systems of each carburetor unit to theassociated engine cylinder with the view in mindof optimizing horsepowerdelivery from each cylinder.

One of the principal objects of the invention is the provision of acarburetor arrangement designed to afford optimum racing performance.

Another of the principal objects of the invention is the provision of acarburetor arrangement affording separate fuel delivery systems for highand low speed nozzles.

Another of the principal objects of the invention is the provision of amulti-barrel carburetor including an air induction housing including aplurality of meshed barrels forming a plurality of carburetor units,together with separate fuel feed means detachably mounted on the airinduction housing for each carburetor unit. Each such separate fuel feedmeans also includes separate high and low speed fuel delivery systems.

Another of the principal objects of the invention is the provision ofseparately controlled fuel feed housings which are adapted to be mountedon an air induction housing including separate high and low speednozzles and which include separate high and low speed fuel deliverysystems.

Other objects and advantages of the invention will become known byreference to the description, claims, and drawings.

DRAWINGS FIG. l is a fragmentary side elevational view of a carburetorarrangement embodying various of the features of the invention.

FIG. 2 is an enlarged fragmentary and partially schematic view takengenerally along line 2-2 of FIG. 1.

FIG. 3 is an end view of the carburetor shown in FIG. i, which view istaken generally along line. 3-3 of FIG. 1. t

, FIG. 4 is a fragmentary view taken along line 4-4 of FIG. 11.

FIG. 5 is an enlarged sectional view taken along line 5-5 of FIG. 3 andshowing, in the upper half, a portion of one carburetor unit and, in thelower half, a portion of a second carburetor unit.

FIG. 6 is an enlarged sectional view taken 6-6 of EEG. d.

Fit]. 7 is an enlarged sectional 7-7 of FIG. 5.

Before explaining the invention in detail,"it is to be understood thatthe invention is not limited in its application to the details ofconstruction and arrangement of parts set forth in the following generaldescription or illustrated in the accompanying drawings, since theinvention is capable of other embodiments and of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology or terminology employed herein is for the purpose ofdescription and not of limitation.

along line view taken along line GENERAL DESCRIPTION Shown fragmentarilyin the drawings is an internal combustion engine 11 including acarburetor arrangement 13 which embodies various features of theinvention. While carburetor arrangements in accordance with theinvention can be employed with engines of various types and can beconstructed differently from the specifically illustrated embodiment,the illustrated engine 11 comprises a four-cylinder, two-stroke engineof the type generally disclosed in U.S. Conover Pat. No. 3,269,374,issued Aug. 30, 1966, which is incorporated herein by reference andexcept that, as will be explained, the reed box-crankcase arrangement inthe disclosed construction does not include an array of four alignedreed valve assemblies as shown at 47 in US. Pat. No. 3,269,374. In theillustrated construction, the cylinders(not specifically shown) extendfrom a crankcase 15 which is sub-divided so as to provide separatecrankcase chambers respectively associated with each of the cylinders.In addition, there is mounted to the engine crankcase 15, a reed box 19including four reed box assemblies or units 21, each associated with aseparate one of the crankcase chambers and each including a conventionalreed valve 23. Because of the general configuration of the crankcase,each reed box unit 21 is generally of rectangular configuration and thereed box units 21 are grouped in laterally adjacent pairs, as shown inFIG. 4.

In accordance with the invention, the carburetor arrangement 13 ismounted on the reed box 19 and includes an air induction housing 25 anda plurality of fuel-feed housings 27.

More particularly, the air induction housing 25 includes (See FIG. 2)two banks 29 of four air induction tubes, passages or barrels 31 withthe air induction tubes 31 in one of the banks 29 being generally innested and closely adjacent relation to the air induction tubes 31 inthe other of the banks 29. Each air induction tube 31 is generally ofidentical construction, including a circular cross section, andconstitutes an air induction passage including (See FIG. an outlet 33communicating with the associated reed box unit 21 and with an inlet 35communicating with the atmosphere. lntermediate the inlet 35 and outlet33 thereof, each barrel or air induction tube 31 can be provided with aventuri section 37. In addition, each barrel or air induction tube 31has pivotally mounted therein a throttle valve 39. Suitable means areprovided for simultaneously operating the throttle valves. One suchmeans including levers 40 which are connected to throttle valve shafts42 and to each other through an adjustable connecting link 44is'shown'in FIG. 2.

The two adjacent barrels or air induction tubes 31 at the end of each ofthe banks 29 constitutes a carburetor unit 41, whereby there areprovided four carburetor units 41 which separately and respectivelycommunicate with the four reed box units 21 and which, in furtheraccordance with the preferred embodiment of the invention, each includetwo barrels or air induction tubes 31 of circular cross section.However, a single barrel with an oblong cross section is within thescope of the invention.

Each of the barrels or air induction tubes 31 in each carburetor unit 41includes (See FIGS. 5 and 7) a main or high speed nozzle 43 comprising atube which projects into the barrel or air induction tube 31 upstreamfrom the throttle valve 39 and includes an outlet preferably located ina plane parallel to the axis of the fuel induction passage 31. Each ofthe high speed nozzles 43 communicates with a respective high speedinlet port 45 at the outer surface of the air induction housing 25.Thus, in the illustrated construction there are two high speed inletports 45 for each carburetor unit 41. However, it is within the scope ofthe invention to provide one high speed inlet port 45 in the airinduction housing 25 for each carburetor unit 41 and to provide internalducting from such a high speed inlet port 45 to as many high speednozzles 43 as are provided in the carburetor unit 41.

One of the barrels or air induction tubes 31 in each carburetor unit 41also includes a secondary or low speed nozzle 47 comprising a series ofopenings 49 which are spaced axially of the barrel or air induction tube31, which include at least one of such openings 49 on each side of thelocation of the throttle valve 39 when in closed position, and whichcommunicates with a well 51 which is open to the outer surface of theair induction housing-25 and which can also be regarded as a low speedinlet port.

The area on the outer surface of the air induction housing 25 in thevicinity of the high speed inlet ports 45 and the low speed well 51 isgenerally planar or flat so as to facilitate sealing against loss offuel when the associated fuel feed housing 27 is mounted on the airinduction housing.

Each of the carburetor units 41 has associated therewith one of thebefore mentioned plurality of fuel feed housings 27 which are allgenerally of identical construction and which are adapted to beremovably mounted on the air induction housing 25 so as to supply fuelto the high speed inlet port 45 and to the low speed well 51 of the airinduction housing 25. Also in accordance with the invention, each fuelfeed housing 27 is preferably constructed (See FIGS. 5, 6, and 7) withtwo mating members, i.e., a housing member 55 and a plate member 57, andso as to include (See FIG. 7) a high speed fuel delivery system 59 and(See FIG. 6) a separate low speed fuel delivery system 61. Each of thehigh speed and low speed fuel delivery systems 59 and 61 includesrespective fuel feed regulating means 63 and 65 each comprisingrespective diaphragm operated fuel flow regulating valves 67 and 69 andrespective metering orifices 71 and 73.

The high speed fuel flow regulating valve 67 includes a valve member 81which is located in a fuel reservoir or chamber 83 formed by 'a recessor cavity 85 in the housing member 55, and which extends from one end ofa centrally pivoted lever 87 for movement relative to a valve seat 89formed at the end of a fuel inlet duct 91 provided in the housing member55 in communication with the high speed fuel chamber 83 and adapted forcommunication with a source of fuel.

The high speed fuel chamber 83 is completed by a diaphragm 93 whichextends between the housing member 55 and the plate member 57 and whichis engaged by the other end of the lever 87 in response to the action ofa spring 95 which also serves to urge the valve member 31 against thevalve seat 89 ,to prevent inflow of fuel from the fuel inlet duct 91.

The plate member 57 is also formed with a cavity or recess 97 which islocated in opposing relation to the high speed fuel chamber 83 on theother side of the diaphragm 93 and which communicates with theatmosphere through a vent 9h.

The high speed fuel chamber 33 also communicates with an outlet duct 99which 'is formed in the housing member 55 and which, in turn,communicates with a threaded bore, duct, or conduit lltlll which isformed in the housing member 35 and which receives a threaded orificeelement 103 including the high speed metering orifice 71l. At its outerend, the threaded bore 1011 is closed by a threaded plug m3 and, at itsinner end, communicates at the interface between the housing member 55and the plate member 57, with a bore or duct 107 in the plate member 57which, in turn, terminates in a high speed outlet port M33 in the outersurface of the plate member 57 in position to communicate, when the fuelfeed housing 27 is mounted on the air induction housing 25, with one ofthe high speed inlet ports 45 of the air induction housing 25.

The duct 107 also communicates with a transverse conduit or duct 111which is formed in the plate member 57, which is plugged at its outerend, and which, in turn, communicates with a duct 113 terminating at theexterior of the platemernber 57 in another high speed outlet port 109located in position, when the fuel feed housing 27 is mounted on the airinduction housing 25, to communicate with the other of the high speedinlet ports 45 of the air induction housing 25. As already indicated,the fuel feed housing 27 can include only one high speed outlet port ifthe air induction housing 25 is formed to include an appropriate conduitsystem communicating with the high speed nozzles 13.

Varying orifices 71 of different sizes can be selectively employed inthe high speed fueldelivery system 59 simply by unthreading the plug W3and substituting a different orifice element M13 with a different sizeorifice 71. If desired, an adjustable needle valve (not shown) could beemployed in lieu of the illustrated orifice element.

The low speed fuel flow regulating valve 63 is is constructed generallyin the same manner as the high speed fuel flow regulating valve 67 andincludes a valve memher 121 extending from a pivoted lever 123 locatedin a fuel chamber or reservoir 325 formed by a recess 1127 in thehousing member 55 on one side of the diaphragm 93. Formed on the otherside of the diaphragm 93 in the plate member 57 is a cavity or recess1129 which communicates with the atmosphere. A spring 13d serves toengage the lever 123 against the diaphragm 93 and to urge the valvemember 1211 toward an inlet valve seat 131.

As with respect to the fuel chamber 83 associated with the high speedfuel flow regulating valve 67, the fuel chamber 125 associated with thelow speed fuel flow regulating valve 69 communicates with a fuel inletduct 132 and with a threaded bore or duct 1133 formed in the housingmember 55 and having located therein a threaded orifice element 135including the low speed orifice 73. At its outer end, the threaded bore133 is closed by a threaded plug 137 and, at its inner end,communicates, at the interface between the housing member 55 and platemember 57, with a bore or duct 139 which extends inthe plate member 57and tenninates at the exterior thereof with a low speed outlet port 141in position to communicate, when the fuel feed housing 27 is mounted onthe air induction housing 25, with the low speed well 31 in the airinduction housing 25.

While the diaphragm operated, fuel flow regulating valves 67 and d9 ofboth the high speed fuel delivery system 33 and the low speed fueldelivery system 61 are generally of identical construction, it isto beunderstood that the construction is not specifically identical and thatthe fuel flow regulating means 63 and 65 respectively of the high andlow speed systems 53 and 61 can be varied from one another, and from onefuel feed housing 27 to another, as desired, to obtain optimumperformance for the particular cylinder with which the fuel deliverysystem is associated. Specifically, and not by way of limitation,various orifice elements can be used and springs or various differentcharacteristics can be used. in addition, the ducts can be sized asdesired. in addition, the diaphramn 33 can be of unitary construction ora separate diaphragm can be employed for each fiiel delivery system.

Accordingly, each of the carburetor units 41 is associated with aseparate fuel feed housing 27 which can be individually constructed soas to serve the associated crankcase chamber 17 and associated cylinderwith optimum performance.

Each fuel feed housing 27 can have a common fuel inlet communicatingwith each of the high speed-and low speed fuel chambers 33 and 1123,respectively. In addition, the fuel feedhousing 27' can be constructedso that the fuel inlet ducts 91 and 132 communicate through a passagesystem (not shown) which, in part, extends through the air inductionhousing 25 for communication with a single fuel inlet line.Alternatively, each fuel feed housing 27 can be individually connectedto a fuel source. i a

in operation, fuel flow from the high speed delivery system 53 to theair induction tubes 31 is-controlled by the air flow within the airinduction tubes 31. Substan: tially no fuel flow occurs when thethrottle valve 39 is closed. However, when the throttle valve 39 is openand the engine 11 is operating at high speed, the flow of air throughthe air induction tubes 31 causes fuel flow from the high speed nozzlesi3.

Fuel flow from the low speed delivery system 61 to the air inductiontubes 31 occurs, when the throttle valve 39 is closed, in response topressure fluctuation occurring in the crankcase chamber 17. Although thelow speed fuel delivery system at also serves, when the throttle valve39 is open, to deliver fuel to the associated air induction tubes 31,the amount of fuel thereby supplied by the low speed delivery system 61is inconsequential compared to the quantity of fuel delivered by thehigh speed delivery system 61. The use of a venturi sleeve 37 in the airinduction tubes or barrels in the area of the high speed nozzles d3 canbe employed to increase the pressures operating on the high speeddiaphragm.

As used herein, the term low speed is meant to encompass operation atboth midrange and idle speeds as compared to high speeds.

Various of the features of the invention are set forth in the followingclaims.

We claim:

it. A carburetor comprising an air induction passage,

.a high speed fuel nozzle communicating with said induction passage, alow speed fuel nozzle communicating with said induction passage, a firstdiaphragm controlled, fuel flow regulating valve communicating with saidhigh speed nozzle and adapted to be connected toa source of fuel, and asecond diaphragm controlled,

fuel flow regulating valve communicating with said low speed nozzle andadapted to be connected to a source of fuel, each of said fuel flowregulating valves comprising a diaphragm subject, on one side, toatmospheric pressure, a pivotally mounted lever having one endengageable with the other side of said diaphragm, a fuel inlet valvemember connected to the other end of said lever and movable relative toa seat provided in a fuel inlet, and means yieldably urging said leverso as to urge said one end of said lever into engagement with saiddiaphragm and so as to urge said valve member into engagement with saidseat to prevent fuel flow from the fuel source to the associated one ofsaid nozzles.

2. A carburetor in accordance with claim 1 wherein said first and secondfuel flow regulating valves have differing operating characteristics.

3. A carburetor in accordance with claim 1 wherein said high speednozzle comprises a tube having an outlet located approximately in aplane parallel to the axis of said fuel induction passage.

4. A carburetor in accordance with claim 1 wherein said fuel inductionpassage includes a venturi section and said high speed nozzlecommunicates with said venturi section.

5. A carburetor in accordance with claim 1 wherein said low speed nozzlecomprises a series of axially spaced outlets communicating with saidfuel induction passage.

6. A carburetor comprising an air induction housing adapted to beconnected to the crankcase of an engine and including a pair of airinduction passages each including a high speed fuel nozzle communicatingwith a high speed fuel inlet port at the exterior surface of said airinduction housing and with at least one of said air induction passagesincluding a low speed fuel nozzle communicating with a low speed fuelinlet port at the exterior surface of said air induction housing, and afuel feed housing adapted to be mounted on said air induction housing inoverlying relation to said high and low speed inlet ports and includinga first diaphragm controlled, fuel flow regulating valve communicatingwith said high speed inlet port in said air induction housing andadapted to be connected to a source of fuel, and a second diaphragmcontrolled, fuel flow regulating valve communicating with said low speedport in said air induction housing and adapted to be connected to asource of fuel.

7. A carburetor in accordance with claim 6 wherein said air inductionhousing includes a pluralityof said pair of air induction passages and alike plurality of said fuel feed housings respectively associated withsaid pairs of air induction passages.

8. A carburetor in accordance with claim 6 wherein said fuel feedhousingincludes a first removably located orifice element locatedbetween said first flow regulating valve and said high speed inlet portand a second removably located orifice element located between saidsecond flow regulating valve and said low speed inlet port.

9. A fuel feed housing adapted to be mounted on a carburetor airinduction housing including high and low speed inlet ports, said fuelfeed housing including means defining first and second fuel chambers,high and low speed outlet ports adapted to respectively communicate withthe high and low speed inlet ports of the air induction housing whensaid fuel feed housing is mounted on the air induction housing, firstand second fuel inlet ducts respectively communicating with said firstand second fuel chambers, first and second fuel outlet ductsrespectively communicating with said first and second fuel chambers andwith said high and low speed outlet ports, a first diaphragm controlled,fuel flow regulating valve in said first fuel chamber, and a seconddiaphragm controlled, fuel flow regulating valve in said second fuelchamber.

10. A carburetor in accordance with claim 9 including first and secondremovably located orifice elements respectively located in said firstand second outlet ducts and respectively including first and secondorifices.

11. A fuel feed housing adapted to be mounted on a carburetor airinduction housing including high and low speed inlet ports, said fuelfeed housing including first and second members connected to each otherin opposing relation to one another, a first pair of first and secondrecesses in one of said members, a second pair of third and fourthrecesses in the other of said members in respective opposing relation tosaid first and second recesses, a diaphragm member interposed betweensaid first and second members and separating said first and secondrecesses from said third and fourth recesses, one of said first andsecond pairs of recesses having communication with the atmosphere andthe other of said first and second pairs of recesses constituting firstand second fuel chambers, high and low speed outlet ports in one of saidmembers adapted to respectively communicate with the high and low speedinlet ports of the air induction housing when said fuel feed housing ismounted on the air induction housing, first and second fuel inlet ductsin said fuel feed hous- Ing respectively communicating with said firstand second fuel chambers, first and second fuel outlet ducts in saidfuel feed housing respectively communicating with said first and secondfuel chambers and with said high and low speed outlet ports, a firstdiaphragm controlled, fuel flow regulating valve in said first fuelchamber, and a second diaphragm controlled, fuel flow regulating valvein said second fuel chamber.

12. A carburetor in accordance with claim 1 1 including first and secondremovably located orifice elements respectively located in said firstand second outlet ducts and respectively including first and secondorifices.

1. A carburetor comprising an air induction passage, a high speed fuelnozzle communicating with said induction passage, a low speed fuelnozzle communicating with said induction passage, a first diaphragmcontrolled, fuel flow regulating valve communicating with said highspeed nozzle and adapted to be connected to a source of fuel, and asecond diaphragm controlled, fuel flow regulating valve communicatingwith said low speed nozzle and adapted to be connected to a source offuel, each of said fuel flow regulating valves comprising a diaphragmsubject, on one side to atmospheric pressure, a pivotally mounted leverhaving one end engageable with the other side of said diaphragm, a fuelinlet valve member connected to the other end of said lever and movablerelative to a seat provided in a fuel inlet, and means yieldably urgingsaid lever so as to urge said one end of said lever into engagement withsaid diaphragm and so as to urge said valve member into engagement withsaid seat to prevent fuel flow from the fuel source to the associatedone of said nozzles.
 2. A carburetor in accordance with claim 1 whereinsaid first and second fuel flow regulating valves have differingoperating characteristics.
 3. A carburetor in accordance with claim 1wherein said high speed nozzle comprises a tube having an outlet locatedapproximately in a plane parallel to the axis of said fuel inductionpassage.
 4. A carburetor in accordance with claim 1 wherein said fuelinduction passage includes a venturi section and said high speed nozzlecommunicates with said venturi section.
 5. A carburetor in accordancewith claim 1 wherein said low speed nozzle comprises a series of axiallyspaced outlets communicating with said fuel induction passage.
 6. Acarburetor comprising an air induction housing adapted to be connectedto the crankcase of an engine and including a pair of air inductionpassages each including a high speed fuel nozzle communicating with ahigh speed fuel inlet port at the exterior surface of said air inductionhousing and with at least one of said air induction passages including alow speed fuel nozzle communicating with a low speed fuel inlet port atthe exterior surface of said air induction housing, and a fuel feedhousing adapted to be mounted on said air induction housing in overlyingrelation to said high and low speed inlet ports and including a firstdiaphragm controlled, fuel flow regulating valve communicating with saidhigh speed inlet port in said air induction housing and adapted to beconnected to a source of fuel, and a second diaphragm controlled, fuelflow regulating valve communicating with said low speed port in said airinduction housing and adapted to be connected to a source of fuel.
 7. Acarburetor in accordance with claim 6 wherein said air induction housingincludes a plurality of said pair of air induction passages and a likeplurality of said fuel feed housings respectively associated with saidpairs of air induction passages.
 8. A carburetor in accordance withclaim 6 wherein said fuel feed housing includes a first removablylocated orifice element located between said first flow regulating valveand said high speed inlet port and a second removably located orificeelement located between said second flow regulating valve and said lowspeed inlet port.
 9. A fuel feed housing adapted to be mounted on acarburetor air induction housing including high and low speed inletports, said fuel feed housing including means defining first and secondfuel chambers, high and low speed outlet ports adapted to respectivelycommunicate with the high and low speed inlet ports of the air inductionhousing when said fuel feed housing is mounted on the air inductionhousing, first and second fuel inlet ducts respectively communicatingwith said first and second fuel chambers, first and second fuel outletducts respectively communicating with said first and second fuelchambers and with said high and low speed outlet ports, a firstdiaphragm controlled, fuel flow regulating valve in said first fuelchamber, and a second diaphragm controlled, fuel flow regulating valvein said second fuel chamber.
 10. A carburetor in accordance with claim 9including first and second removably located orifice elementsrespectively located in said first and second outlet ducts andrespectively including first and second orifices.
 11. A fuel feedhousing adapted to be mounted on a carburetor air induction housingincluding high and low speed inlet ports, said fuel feed housingincluding first and second members connected to each other in opposingrelation to one another, a first pair of first and second recesses inone of said members, a second pair of third and fourth recesses in theother of said members in respective opposing relation to said first andsecond recesses, a diaphragm member interposed between said first andsecond members and separating said first and second recesses from saidthird and fourth recesses, one of said first and second pairs ofrecesses having communication with the atmosphere and the other of saidfirst and second pairs of recesses constituting first and second fuelchambers, high and low speed outlet ports in one of said members adaptedto respectively communicate with the high and low speed inlet ports ofthe air induction housing when said fuel feed housing is mounted on theair induction housing, first and second fuel inlet ducts in said fuelfeed housIng respectively communicating with said first and second fuelchambers, first and second fuel outlet ducts in said fuel feed housingrespectively communicating with said first and second fuel chambers andwith said high and low speed outlet ports, a first diaphragm controlled,fuel flow regulating valve in said first fuel chamber, and a seconddiaphragm controlled, fuel flow regulating valve in said second fuelchamber.
 12. A carburetor in accordance with claim 11 including firstand second removably located orifice elements respectively located insaid first and second outlet ducts and respectively including first andsecond orifices.